promesa.core — funcool/promesa 11.0.678

-> clj/s macro

(-> x & forms)

Like the clojure.core/->, but it will handle promises in values and make sure the next form gets the value realized instead of the promise.

Example fetching data in the browser with CLJS:

(p/-> (js/fetch #js {...}) ; returns a promise .-body)

The result of a thread is a promise that will resolve to the end of the thread chain.

->> clj/s macro

(->> x & forms)

Like the clojure.core/->>, but it will handle promises in values and make sure the next form gets the value realized instead of the promise.

Example fetching data in the browser with CLJS:

(p/->> (js/fetch #js {...}) ; returns a promise .-body read-string (mapv inc)

The result of a thread is a promise that will resolve to the end of the thread chain.

all clj/s

(all promises)

Given an array of promises, return a promise that is fulfilled when all the items in the array are fulfilled.

Example:

(-> (p/all [(promise :first-promise)
            (promise :second-promise)])
    (then (fn [[first-result second-result]])
            (println (str first-result ", " second-result))))

Will print to out :first-promise, :second-promise.

If at least one of the promises is rejected, the resulting promise will be rejected.

any clj/s

(any promises)

(any promises default)

Given an array of promises, return a promise that is fulfilled when first one item in the array is fulfilled.

as-> clj/s macro

(as-> expr name & forms)

Like clojure.core/as->, but it will handle promises in values and make sure the next form gets the value realized instead of the promise.

await clj

(await resource)

(await resource duration)

A exception safer variant of await!. Returns nil on timeout exception, forwards interrupted exception and all other exceptions are returned as value, so user is responsible for checking if the returned value is exception or not.

await! clj

(await! resource)

(await! resource duration)

Generic await operation. Block current thread until some operation terminates. Returns nil on timeout; does not catch any other exception.

Default implementation for Thread, CompletableFuture and CountDownLatch.

The return value is implementation specific.

bind clj/s

(bind p f)

(bind p f executor)

Chains a function f to be executed with when the promise p is successfully resolved. Returns a promise that will mirror the promise instance returned by calling f with the value as single argument; f must return a promise instance.

The computation will be executed in the completion thread by default; you also can provide a custom executor.

cancel! clj/s

(cancel! p)

Cancel the promise.

cancelled? clj/s

(cancelled? v)

Return true if v is a cancelled promise.

catch clj/s

(catch p f)

(catch p pred-or-type f)

Chains a function f to be executed when the promise p is rejected. Returns a promise that will be resolved with the return value of calling f with exception as single argument; f can return a plain value or promise instance, an automatic unwrapping will be performed.

The computation will be executed in the completion thread, look at merr if you want the ability to schedule the computation to other thread.

chain clj/s

(chain p f)

(chain p f & fs)

Chain variable number of functions to be executed serially using then.

chain' clj/s

(chain' p f)

(chain' p f & fs)

Chain variable number of functions to be executed serially using map.

create clj/s

(create f)

(create f executor)

Create a promise instance from a factory function. If an executor is provided, the factory will be executed in the provided executor.

A factory function looks like (fn [resolve reject] (resolve 1)).

deferred clj/s

(deferred)

Creates an empty promise instance.

deferred? clj/s

(deferred? v)

Return true if v is a deferred instance.

delay clj/s

(delay t)

(delay t v)

(delay t v scheduler)

Given a timeout in miliseconds and optional value, returns a promise that will be fulfilled with provided value (or nil) after the time is reached.

do clj/s macro

(do & exprs)

Execute potentially side effectful code and return a promise resolved to the last expression after awaiting the result of each expression.

do! clj/s macro

(do! & exprs)

A convenience alias for do macro.

do* clj/s macro

(do* & exprs)

An exception unsafe do-like macro. Supposes that we are already wrapped in promise context so avoids defensive wrapping.

done? clj/s

(done? p)

Returns true if promise p is already done.

doseq clj/s macro

(doseq [binding xs] & body)

Simplified version of doseq which takes one binding and a seq, and runs over it using promesa.core/run!

error clj/s

(error f p)

(error f type p)

Same as catch but with parameters inverted.

DEPRECATED

extract clj/s

(extract p)

(extract p default)

Returns the current promise value.

finally clj/s

(finally p f)

(finally p f executor)

Like handle but ignores the return value. Returns a promise that will mirror the original one.

fmap clj/s

(fmap f p)

(fmap executor f p)

A convenience alias for map.

fnly clj/s

(fnly f p)

(fnly executor f p)

Inverted arguments version of finally; intended to be used with ->>.

future clj/s macro

(future & body)

Analogous macro to clojure.core/future that returns promise instance instead of the Future. Exposed just for convenience and works as an alias to thread.

handle clj/s

(handle p f)

(handle p f executor)

Chains a function f to be executed when the promise p is completed (resolved or rejected) and returns a promise completed (resolving or rejecting) with the return value of calling f with both: value and the exception; f can return a new plain value or promise instance, and automatic unwrapping will be performed.

The computation will be executed in the completion thread by default; you also can provide a custom executor.

For performance sensitive code, look at hmap and hcat.

hcat clj/s

(hcat f p)

(hcat executor f p)

Chains a function f to be executed when the promise p is completed (resolved or rejected) and returns a promise that will mirror the promise instance returned by calling f with both: value and the exception. The f function must return a promise instance.

The computation will be executed in the completion thread by default; you also can provide a custom executor.

Intended to be used with ->>.

hmap clj/s

(hmap f p)

(hmap executor f p)

Chains a function f to be executed when the promise p is completed (resolved or rejected) and returns a promise completed (resolving or rejecting) with the return value of calling f with both: value and the exception.

The computation will be executed in the completion thread by default; you also can provide a custom executor.

Intended to be used with ->>.

let clj/s macro

(let bindings & body)

A let alternative that always returns promise and waits for all the promises on the bindings.

let* clj/s macro

(let* bindings & body)

An exception unsafe let-like macro. Supposes that we are already wrapped in promise context so avoids defensive wrapping.

loop clj/s macro

(loop bindings & body)

map clj/s

(map f p)

(map executor f p)

Chains a function f to be executed when the promise p is successfully resolved. Returns a promise that will be resolved with the return value of calling f with value as single argument.

The computation will be executed in the completion thread by default; you also can provide a custom executor.

This function is intended to be used with ->>.

mapcat clj/s

(mapcat f p)

(mapcat executor f p)

Chains a function f to be executed when the promise p is successfully resolved. Returns a promise that will mirror the promise instance returned by calling f with the value as single argument; f must return a promise instance.

The computation will be executed in the completion thread by default; you also can provide a custom executor.

This funciton is intended to be used with ->>.

mcat clj/s

(mcat f p)

(mcat executor f p)

A convenience alias for mapcat.

merr clj/s

(merr f p)

(merr executor f p)

Chains a function f to be executed when the promise p is rejected. Returns a promise that will mirror the promise returned by calling f with exception as single argument; f must return a promise instance or throw an exception.

The computation will be executed in the completion thread by default; you also can provide a custom executor.

This is intended to be used with ->>.

pending? clj/s

(pending? p)

Returns true if promise p is stil pending.

plet clj/s macro

(plet bindings & body)

A parallel let; executes all the bindings in parallel and when all bindings are resolved, executes the body.

promise clj/s

(promise v)

(promise v executor)

The coerce based promise constructor. Creates an appropriate promise instance depending on the provided value.

If an executor is provided, it will be used to resolve this promise.

promise? clj/s

(promise? v)

Return true if v is a promise instance.

promisify clj/s

(promisify callable)

Given a function that accepts a callback as the last argument, return a function that returns a promise. Callback is expected to take one parameter (result of a computation).

race clj/s

(race promises)

recur clj/s macro

(recur & args)

recur? clj/s

(recur? o)

reject! clj/s

(reject! p e)

Reject a completable promise with an error.

rejected clj/s

(rejected v)

Return a rejected promise with provided reason.

rejected? clj/s

(rejected? p)

Returns true if promise p is already rejected.

resolve! clj/s

(resolve! o)

(resolve! o v)

Resolve a completable promise with a value.

resolved clj/s

(resolved v)

Return a resolved promise with provided value.

resolved? clj/s

(resolved? p)

Returns true if promise p is already fulfilled.

run! clj/s

(run! f coll)

(run! f coll executor)

A promise aware run! function. Executed in terms of then rules.

then clj/s

(then p f)

(then p f executor)

Chains a function f to be executed when the promise p is successfully resolved. Returns a promise that will be resolved with the return value of calling f with value as single argument; f can return a plain value or promise instance, an automatic unwrapping will be performed.

The computation will be executed in the completion thread by default; you also can provide a custom executor.

then' clj/s

(then' p f)

(then' p f executor)

Chains a function f to be executed when the promise p is successfully resolved. Returns a promise that will be resolved with the return value of calling f with value as single argument; f should return a plain value, no automatic unwrapping will be performed.

The computation will be executed in the completion thread by default; you also can provide a custom executor.

thenable? cljs

(thenable? v)

Returns true if v is a promise like object.

thread clj/s macro

(thread & body)

Analogous to clojure.core.async/thread that returns a promise instance instead of the Future.

thread-call clj/s

(thread-call f)

(thread-call executor f)

Analogous to clojure.core.async/thread that returns a promise instance instead of the Future. Useful for executing synchronous code in a separate thread (also works in cljs).

timeout clj/s

(timeout p t)

(timeout p t v)

(timeout p t v scheduler)

Returns a cancellable promise that will be fulfilled with this promise's fulfillment value or rejection reason. However, if this promise is not fulfilled or rejected within ms milliseconds, the returned promise is cancelled with a TimeoutError.

TimeoutException cljs

(TimeoutException message)

vthread clj/s macro

(vthread & body)

Analogous to clojure.core.async/thread that returns a promise instance instead of the Future. Useful for executing synchronous code in a separate thread (also works in cljs).

vthread-call clj/s

(vthread-call f)

A shortcut for (p/thread-call :vthread f).

wait-all clj/s

(wait-all & promises)

Given a variable number of promises, returns a promise which resolves to nil when all provided promises complete (rejected or resolved).

EXPERIMENTAL

wait-all! clj

(wait-all! promises)

A blocking version of wait-all.

wait-all* clj/s

(wait-all* promises)

Given an array of promises, return a promise that is fulfilled when all the items in the array are resolved (independently if successfully or exceptionally).

Example:

(->> (p/wait-all* [(promise :first-promise)
                   (promise :second-promise)])
     (p/fmap (fn [_]
               (println "done"))))

Rejected promises also counts as resolved.

with-redefs clj/s macro

(with-redefs bindings & body)

Like clojure.core/with-redefs, but it will handle promises in body and wait until they resolve or reject before restoring the bindings. Useful for mocking async APIs.

wrap clj/s

(wrap v)

A convenience alias for promise coercion function that only accepts a single argument.